Unit 3 Nutritional Process

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Unit 3 The Nutritional Process


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Index

1. Introduction

2. Digestive system

3. Respiratory system

4. Circulatory system

5. Excretory system


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1. Introduction

There are 4 system involved in nutrition:Digestive system:

- digestive tract

-associated glands

Respiratory system:

-respiratory paths

-lungs

Circulatory system:

-heart

-blood

-blood vessels

Excretory system:

-kidneys

-urinary tracts


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Products expelled Organ

Carbon dioxide Lungs

Urea, water and salts Kidneys

Faeces Intestin

Substances which enter the organism:

airwater

foods

Products expelled by the organism (waste products)


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2.2 The digestive process

There are three phases in food processing:

-Digestion(mouth, stomach and small intestine)separation of substances (nutrients)

that can be used from the food

-Absorption(small intestine) nutrients pass into the

bloodstream

-Expulsion of waste (large intestine)unusable substancesare expelled


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PERISTALTIC MOVEMENTS = Movement of food through the digestive tract. It consists

on the narrowing of the tube through the contraction of the muscles of the walls,what pushes the food.


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2.3 Digestion

A. Types of digestion

Mechanical digestioncutting, crushing food(physical changes)

Chemical digesionsubstances attack the food and

break it down into smaller chemical compounds (nutrients)


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B. Stages of digestion

In the mouthmastication and salivation take place

The salivary glands produce saliva, a liquid containing digestive enzymes (which act

chemically on the food)

Chemical digestion in the mouthamylase breaks down the starch into maltose

DIGESTION

starch maltoses

DIGESTION

Physical digestionChemical digestion


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In thestomach begins gastric digestion

(both physical and chemical digestion take place

simultaneously)

Movement of the walls of the stomach Food is mixed with the gastric juices,

which contain HCl and enzymes

http://www.youtube.com/watch?v=URHBBE3RKEs = gastric digestion

As a result of gastric digestion, a pulp known as chymeleaves the stomach via the pylorus
http://www.youtube.com/watch?v=URHBBE3RKEshttp://www.youtube.com/watch?v=URHBBE3RKEs


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First section of the small intestine

(duodenum)

Chemical digestionthe chyme is mixed with

intestinal juices. They come from

the walls of the duodenum

the liverproduces bile

the pancreasproduces pancreatic juice

The result is called chyle


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2.4 Absorption (in the jejunum and illeon)

The digested food (nutrients) passes into the

bloodstream through the intestineswalls.

The walls of the intestine are filled with intestinal hairs (deep folds in the wall and many

blood vessels)this increases the efficiency of absorption considerably.


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Functions

water and some ions pass into the bloodstream (absorption of

water and ions)

faeces are released through the anus

2.5 Large intestine

Leftovers and water arrive to the large

intestine.

Page 65, activities 1 and 3

http://www.youtube.com/watch?v=IxNpXO8gGFM&feature=related = digestion and absorption
http://www.youtube.com/watch?v=IxNpXO8gGFM&feature=relatedhttp://www.youtube.com/watch?v=IxNpXO8gGFM&feature=related


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3. Respiratory system

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Unit 3 Nutritional Process